Antimicrobials are used as prophylactics, growth promoters, and therapeutics in livestock production. Low doses of antimicrobials are administered for a long time to promote growth, whereas prophylactic antimicrobials are administered in small doses to prevent disease. Although the duration of antimicrobial use varies for prophylaxis and growth promotion, both dosages are typically considered sub-therapeutic, which is linked to the development of AMR (Er et al., 2013). New forms of AMR may appear and easily cross international boundaries and spread across the continents. World health leaders have described antimicrobial-resistant microorganisms as “nightmare bacteria” that “pose a catastrophic threat” to people worldwide (CDC, 2019).

Trends in AMR have evolved over the years, and understanding how these trends emerge is critical for the development of efficient strategies to address this growing threat (Hwang and Gums, 2016). The primary focus of AMR was hospital-acquired infections, particularly those caused by multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) (Frieri et al., 2017). However, during the last few decades, there has been a shift toward community-acquired infections caused by antibiotic-resistant strains of bacteria such as Klebsiella pneumoniae, Streptococcus pneumoniae, Acinetobacter baumannii, and Escherichia coli (Levy, 2005). P. falciparum to Sulfadoxine-pyrimethamine was observed in south-east Asia and later emerged in Africa, which necessitates effective monitoring and selective use of antimalarial drugs to prevent resistant strains’ spread (Conrad and Rosenthal, 2019). One of the most common invasive fungal infections, Candida auris, has become highly drug-resistant. It is widespread and shows increased resistance to Fluconazole, Amphotericin B, and Voriconazole. The emergence of Caspofungin resistance has also been reported (Sanyaolu et al., 2022).

Trends in AMR drivers vary across geographical regions. In low-income countries, the burden of AMR is high due to factors such as poor sanitation, lack of access to laboratory diagnostics, insufficient healthcare resources, limited choice of drugs, and unavailability of standard drugs (Iskandar et al., 2021). In high-income countries, efforts have been made to reduce the use of antimicrobials in healthcare and agriculture; however, there is still growing concern regarding the emergence of resistant bacteria in the community (Paphitou, 2013). 

In terms of the specific types of infections, there are significant differences in the rates of AMR. For example, in the United States, S. aureus and Enterococcus spp. have high rates of resistance. In Europe, there are high rates of resistance among Streptococcus pneumoniae and Escherichia coli strains. In Asia, there are high rates of resistance in Klebsiella pneumoniae and Acinetobacter baumannii. At an alarming rate, certain pathogens are becoming increasingly resistant to antimicrobials, and the WHO has created a list of priority bacterial pathogens (see Table 1) (Hashiguchi et al., 2019).

OPEN IN VIEWERTable 1. List of priority pathogens for research and development of new antimicrobials to combat AMR compiled by the WHO.

Species

Type of antibiotic resistance

Medium

1. Streptococcus pneumoniae
2. Penicillin-non-susceptible
3. Haemophilus influenzae
4. Ampicillin-resistant
5. Shigella spp.
6. Fluoroquinolone-resistant

High

1. Enterococcus faecium
2. Vancomycin-resistant
3. Staphylococcus aureus
4. Methicillin-resistant, vancomycin-intermediate and resistant
5. Helicobacter pylori
6. Clarithromycin-resistant
7. Campylobacter spp.
8. Fluoroquinolone-resistant
9. Salmonellae
10. Fluoroquinolone-resistant
11. Neisseria gonorrhoeae
12. Cephalosporin-resistant, fluoroquinolone-resistant

Critical

1. Acinetobacter baumannii
2. Carbapenem-resistant
3. Pseudomonas aeruginosa
4. Carbapenem-resistant
5. Enterobacteriaceae
6. Carbapenem-resistant, ESBL-producing

Antimicrobial resistance drivers in East African pastoral systems

Pastoral systems are land-based systems occurring in areas with low rainfall and are associated with grazing ruminants as the predominant form of land use. They are mainly found in arid and semi-arid zones of West and East Africa and are not prevalent in the humid zone. Pastoral systems can be categorized into three types based on rainfall range, including nomadic pastoralism, transhumant pastoralism, and agro-pastoralism (see Fig. 2) (Steinfeld and Mäki-Hokkonen, 1995). The latter is associated with dryland or rain-fed cropping and animals range over short distances. Agro-pastoralism includes village-based herders and pastoral households, which rely on both farming and pastoralism for household income (Chinasho et al., 2017).

Recent studies have highlighted the increasing concerns regarding AMR in pastoral settings. In these settings, antimicrobial use in animal health is often unregulated, inappropriate, and linked to poor animal welfare practices (Sadiq et al., 2018; Ngaywa et al., 2019; Mutua et al., 2020; Gemeda et al., 2021). This leads to the selection and dissemination of antimicrobial-resistant bacteria in the environment and food chain, thereby increasing the risk of zoonotic infections and treatment failure. Limited access to adequate veterinary care, diagnostic tools, and affordable alternatives to antimicrobials exacerbates the problem of AMR in African pastoral communities (Grace et al., 2016).

In different East African countries, various AMR studies were conducted and some of them are summarized in Table 2. These studies covered topics such as malaria-causing pathogens, anthelmintic resistance in nematodes affecting sheep and goats, and antifungal drug susceptibility of pathogens causing meningitis, Candida subspecies susceptibility, inappropriate usage of antimicrobials with Pseudomonas aeruginosa strains, and antibiotic resistance in bacterial isolates affecting cows. The studies revealed the varied nature of AMR in different pathogens, hosts, and settings in East Africa.

Overuse of antimicrobials

Generally, animal diseases in pastoral regions cause notable financial and socio-economic hardship for livestock owners in Africa. These losses are particularly severe in remote areas, where communities depend solely on their livestock for survival. Unfortunately, providing veterinary services in these areas is challenging because of the insufficient infrastructure and limited resources. Additionally, as pastoral communities are small and mobile, they can be difficult to reach as they travel far in search of grazing and water, and they are mostly excluded from most veterinary and public health services (Desta, 2015).

The lack of veterinary services, poor animal healthcare systems, and inadequate regulatory capacities to promote prudent use of antimicrobials are among the various factors driving the overuse of antimicrobials in pastoral areas (Frumence et al., 2021). Consequently, there is an increased likelihood that pastoralists will self-medicate their animals, often using antimicrobials in ways that can contribute to the emergence of AMR. 

These antimicrobials may not be appropriately administered in terms of dosage and the treatment course may be shortened. Such practices are believed to have led to the emergence of AMR in pastoral settings (Alonso et al., 2017; Van et al., 2020). Antimicrobial overuse in pastoral areas is becoming a significant factor responsible for the emergence of AMR, which is an increasing concern for human and animal health (Gemeda et al., 2020).

Lack of veterinary services and AMR surveillance

Another factor contributing to the spread of AMR in pastoral settings is the lack of veterinary services. In many rural areas, veterinary services are not widely available, and the drugs prescribed by veterinarians are often expensive. This leaves pastoralists with no option but to rely on self-medication and drug sellers do not always provide accurate information on the usage and dosage of antimicrobials (Gebeyehu et al., 2021).

Access to veterinary services is critical to safeguard animal health and control the spread of antimicrobial-resistant bacteria. However, many pastoral areas lack access to veterinary services and farmers rely on non-qualified individuals to treat their livestock. This often leads to the misuse of antimicrobials, which accelerates the development of AMR bacteria (Manyi-Loh et al., 2018). Limited access to veterinary services makes it difficult to accurately diagnose bacterial infections and to prescribe appropriate antimicrobials. Similarly, there is inadequate surveillance of AMR in livestock, owing to the lack of veterinary services, which increases the risk of transmission from animals to humans. 

Additionally, veterinarians in pastoral areas face challenges such as a lack of training, resources, and medicines, which decrease their effectiveness in controlling the spread of AMR. Thus, the absence of timely treatment for animal diseases leading to chronic infections necessitates repeated antibiotic use, which increases the risk of resistance (Grace, 2015). Addressing this issue requires investment in veterinary infrastructure, training of veterinary professionals, and ensuring access to affordable and effective antimicrobials for farmers and herders. It is essential to recognize the important role that animal health plays in preventing the development and spread of AMR and ensuring that veterinary services are available to all communities, regardless of their location (Feyera et al., 2017; WHO, 2022).

Poor husbandry practices

Poor husbandry practices in pastoral settings are significant factors that contribute to the dissemination of antimicrobial-resistant bacteria. In these settings, animals are kept near humans, which increases the possibility of bacterial transmission from animals to humans (Klous et al., 2016; Ellwanger and Chies, 2021). Inadequate sanitation infrastructure and limited access to uncontaminated water sources are additional factors that contribute to the dissemination of bacteria in both animal and human populations. The probability of bacterial transmission and persistence is amplified when waste management standards are not effectively established, thereby providing a breeding ground for bacterial proliferation (Karn et al., 2012; Gwimbi et al., 2019).

Poor hygiene and sanitation conditions in pastoral settings increase the risk of bacterial transmission and propagation of resistance, making the control of AMR bacteria an enormous challenge. This highlights the importance of maintaining robust hygiene and waste management practices to control AMR spread. Proper implementation of hygiene and sanitation measures may be critical in curbing the transmission of antibiotic-resistant infections in human and animal populations (Musoke et al., 2021).

Unregulated use of antimicrobials in livestock

In pastoral settings, regulations on AMU in livestock are poorly enforced and livestock owners have easy access to veterinary drugs. Consequently, pastoralists frequently use antimicrobials to treat sick animals, leading to the unnecessary use of antimicrobials. This can ultimately result in the selection of resistant bacteria that can spread from person to person and become more difficult to treat (Grace et al., 2016). Antimicrobials can be purchased without a prescription or veterinary advice in many pastoral settings, leading to the overuse and misuse of antimicrobials in livestock, the unregulated use of antimicrobials in livestock is an additional factor that contributes to the spread of AMR bacteria in humans and the environment (Fig. 3) (Gebeyehu et al., 2021).

Lack of awareness

The lack of awareness regarding the emergence of AMR is a significant factor contributing to the spread of AMR, as it leads to imprudent use of antimicrobials in pastoral areas (Mutua et al., 2020). Most pastoralists are not aware of the harmful effects related to the excessive use of antimicrobials or the emergence of AMR bacteria (Sadiq et al., 2018). Moreover, pastoralists may not be able to adhere to recommended drug withdrawal periods. Consequently, antimicrobial-contaminated milk and meat are prevalent (Gemeda et al., 2020). Thus, the combination of limited knowledge of AMR risks and subsequent lack of compliance with drug withdrawal periods poses serious public health concerns. The emergence of antibiotic-resistant bacteria can lead to reduced access to effective treatments, increased morbidity and mortality rates, and the potential transmission of antibiotic-resistant bacteria from animals to humans, leading to the emergence of incurable infectious diseases. Therefore, it is essential to implement awareness-raising measures and ensure compliance with drug withdrawal periods to promote the responsible use of antimicrobials, preserve their efficacy, and protect animal and human health (O’Neill, 2016).

Limited access to vaccines

Limited access to vaccines in pastoral areas can increase the use of antimicrobials, leading to antimicrobial-resistant bacteria and the exacerbation of treatable diseases. Vaccines are crucial for preventing livestock diseases and for decreasing the need for antimicrobial use. Nonetheless, numerous factors such as distance, seasonality, and infrastructure challenges contribute to inadequate access to vaccines (Alghamdi, 2021). The use of antimicrobials to treat such infections can lead to AMR. These bacteria can affect both human and animal health, rendering the treatment of infections challenging. The emergence of AMR bacteria is a significant public health concern that can lead to higher healthcare costs and increased mortality rates (Gemeda et al., 2020).

Therefore, it is crucial to ensure that vaccines and other animal health services are accessible to pastoral communities to prevent AMR. This can be achieved by developing effective partnerships between governments, non-governmental organizations, and communities to ensure that vaccines are readily available and accessible to those who need them (Rosini et al., 2020).

Inappropriate use of antimicrobials in humans

The inappropriate use of antimicrobials in human health, such as self-medication, over-prescription, and poor adherence to treatment, contributes to the spread of antimicrobial-resistant microorganisms. Such malpractices promote the selective survival and proliferation of microorganisms that possess inherent or acquired resistance to antimicrobials, leading to the emergence of treatment-resistant strains (Dache et al., 2021).

Furthermore, in pastoral areas where medical facilities are scarce, some people may have no recourse and resort to self-medication or traditional remedies, such as antimicrobials, without adhering to conventional healthcare guidelines. Self-medication and lack of adherence to healthcare guidelines increase the likelihood of unwarranted use of antimicrobials, thereby promoting the development of AMR bacteria (Mendelson et al., 2016).

Impact of antimicrobial resistance in pastoral settings

ECONOMIC IMPACT

According to estimates, livestock accounts for 73% of worldwide antimicrobial use. Sales data from 41 countries were examined as part of a recent study, which predicted an 11.5% increase in AMU from 2017 to 2030. This increase is expected to be concentrated mainly in LMICs (Tiseo et al., 2020; Mulchandani et al., 2023).

According to current estimations, AMR could lead to the loss of 10 million lives per year, force millions of households into extreme poverty, and cause an economic burden of up to USD 100 trillion globally by 2050 (Dadgostar, 2019; WHO, 2019).

The emergence of AMR bacteria in pastoral settings has affected the economy of the pastoralists. This is because curable animal diseases are difficult to treat, resulting in increased costs for animal healthcare. Additionally, the development and spread of untreatable diseases may lead to increased mortality in animals. This in turn affects the livelihood of pastoralists by reducing livestock productivity and the quantity of animal products available for sale. The combination of reduced productivity and increased healthcare costs may significantly impact pastoralists’ incomes and financial stability. Addressing AMR in pastoral settings is essential to preserve the integrity of the food supply and ensure the economic sustainability of pastoralists (Kimera et al., 2020).

PUBLIC HEALTH IMPACT

Antimicrobial-resistant bacteria pose a significant risk to public health. In pastoral areas, animals and humans often live in close proximity, which presents a high likelihood of bacterial transmission from animals to humans (Katale et al., 2020). The spread of AMR bacteria from animals to humans in these settings is relatively common, which implies that infectious diseases that may be difficult or impossible to treat with available antimicrobials can emerge (Alhaji and Isola, 2018). The close interaction between animals and humans in pastoral settings enhances human exposure to AMR bacteria present in animal excreta or direct contact with animal products (Manyi-Loh et al., 2018). Therefore, AMR bacteria in pastoral environments are a major public health concern. The transmission of antibiotic-resistant bacteria from animals to humans increases the risk of developing diseases that are difficult to treat, leading to higher morbidity and mortality rates. Effective measures must be implemented to limit the emergence of AMR bacteria in pastoral areas to preserve public health, promote the use of antimicrobials, and reduce the spread of antibiotic resistance from animals to humans (Landers et al., 2012).

ENVIRONMENTAL IMPACT

Significant amounts of antimicrobials administered to animals and humans are primarily excreted in urine and manure. Once excreted, residual traces of antimicrobials and their metabolites may enter water bodies, soil, or air, where they can persist for prolonged periods. Such antibiotic residues can affect the natural microbial balance in the environment, making it easier for resistant bacteria to thrive. Additionally, antibiotic residues in the environment can promote the selection of resistant bacteria and accelerate AMR emergence. These resistant bacteria can spread from animals to humans, contributing to growing public health concerns associated with AMR. Therefore, there is a need to implement strict regulations on the use of antimicrobials to minimize the environmental impact of antibiotic use in pastoral areas. This, coupled with promoting the responsible use of antimicrobials, can contribute to reducing the emergence and spread of antibiotic-resistant bacteria in the environment (Kumar et al., 2005).

Containment of antimicrobial use in pastoral settings

The containment of antimicrobial use in pastoral settings is crucial for sustaining animal production and promoting antimicrobial use. Pastoralist communities are particularly vulnerable to AMR because of limited access to veterinary services, poor hygienic conditions, and the extensive use of antimicrobials (Pinto, 2020). Addressing the issue of antimicrobial use in pastoral settings requires the implementation of a comprehensive, multifaceted strategy, including education and awareness-raising campaigns, promotion of better animal husbandry practices, stringent regulatory and monitoring measures, alternative remedies, active surveillance of disease outbreaks, effective antimicrobial stewardship programmes, increased access to veterinary and healthcare services, and proper regulation of animal markets (Rousham et al., 2018). Governments and non-governmental organizations must prioritize investments in disease surveillance systems, veterinary capacity, and diagnostic tools; enact policies to regulate the use of antimicrobials in animal production; establish appropriate penalties for non-compliance; and support the implementation of best practices. Collaboration among animal health experts, policy makers, and community stakeholders is essential for providing sustainable solutions to tackle AMR in pastoral areas (WHO, 2012; Chua et al., 2021).

EDUCATION AND AWARENESS-RAISING

Education is a critical component in the containment of antimicrobial use in pastoral settings. As AMR is a complex and global problem, the dissemination of information to farmers and pastoralists can help raise awareness and promote the responsible use of antimicrobials. For example, educating pastoral communities on the dangers of antimicrobial misuse, the importance of completing prescribed treatments, and the significance of seeking veterinary services for animal health concerns can contribute positively to reducing the spread of AMR bacteria (Ahmad et al., 2023).

Regulation

Regulating the use of antimicrobials is crucial to ensure that only legitimate antimicrobials are used for animal health. Veterinary professionals need to have specified guidelines and regulations in place to guide the appropriate use of antimicrobials. The regulation of antimicrobials should be defined and enforced by veterinary regulatory authorities, and illegal importation of antimicrobials should be prevented. Veterinary regulations should also include the requirement for farmers and pastoralists to report antibiotic use to veterinary authorities. Governments should enact policies to regulate the use of antimicrobials in animal production, establish appropriate penalties for non-compliance, and support the implementation of best practices (WHO, 2020).

ONE HEALTH ADOPTION FOR AMR MANAGEMENT

AMR is a global problem affecting human, animal, and environmental health. The One Health approach is a holistic approach that recognizes the interconnectedness of human, animal, and environmental health. It emphasizes the link between human and animal health and the environment, and the need to work together across sectors to address AMR. (Erkyihun et al., 2022). The One Health approach to AMR management should be based on the following strategies:

ANTIMICROBIAL STEWARDSHIP

Antimicrobial stewardship is a key component of the One Health approach to AMR management. It involves the use of antimicrobials, the promotion of appropriate prescribing practices, and the reduction of unnecessary antibiotic use in humans and animals. Antimicrobial stewardship programmes should be implemented in both human and animal health settings to ensure the responsible use of antimicrobials (Walsh, 2018; Musoke et al., 2020).

SURVEILLANCE AND MONITORING

Surveillance and monitoring are critical components of the One Health approach to AMR management. This involves the collection and analysis of data on AMR in humans, animals, and the environment. Surveillance systems should be established to monitor the use and resistance to antimicrobials in humans, animals, and the environment. The data collected should be analysed and used to inform policy decisions and public health actions (WHO, 2016; Seale et al., 2017).

INFECTION PREVENTION AND CONTROL

Enhancing access to veterinary services and diagnostic tools is essential to control the spread of AMR in pastoral areas. Governments and non-governmental organizations must prioritize investments in disease surveillance systems, veterinary capacity, and diagnostic tools. Moreover, collaboration among animal health experts, policy makers, and community stakeholders is essential to provide sustainable solutions to tackle AMR in pastoral areas (Jaime et al., 2022). Infection prevention and control measures are essential for preventing the spread of AMR. This includes the use of vaccines, proper hygiene practices, and personal protective equipment. Infection prevention and control measures should be implemented in both human and animal health settings to reduce the risk of transmission of resistant organisms (Sharma et al., 2022).

RESEARCH AND DEVELOPMENT

Research and development are essential to develop new antimicrobials and alternative therapies to combat AMR. The One Health approach promotes collaborative research to develop new antimicrobial agents, vaccines, and alternative therapies. Research should also focus on understanding the mechanisms of AMR, transmission pathways, and the impact of environmental factors on the spread of resistant bacteria (Miethke et al., 2021).

Conclusion

Antimicrobial resistance is a significant concern in pastoral settings, particularly in LMICs where overuse and misuse of antimicrobials in animal production, poor animal husbandry practices, and inadequate public health facilities have contributed significantly to the emergence and spread of antimicrobial-resistant pathogens. To mitigate the risks of AMR in African pastoral settings, it is essential to prioritize the development and implementation of stringent regulatory frameworks and promote scientific research. This will facilitate the monitoring of antimicrobial use and resistance patterns in livestock and humans, and help to guide evidence-based policies and interventions. Concrete measures and appropriate policies should be implemented to promote a One Health approach that will ultimately result in better health outcomes for both livestock and humans. Stakeholders, including veterinary and human health professionals, policy makers, and communities, can work together to promote the rational use of antimicrobials, protect animal and human health, and prevent the emergence and spread of drug-resistant microbes in pastoral areas. By adopting a One Health approach, we can address the complex challenges of AMR in pastoral settings, improve livestock and human health, and secure sustainable livelihoods for pastoral communities.